The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be inventions.
Total hip replacement refers to a surgical procedure where a hip joint is replaced using a prosthetic implant. There are several different techniques that may be used, but all include a step of inserting an acetabular component into the acetabulum and positioning it correctly in three dimensions (along an X, Y, and Z axis).
In total hip replacement (THR) procedures there are advantages to patient outcome when the procedure is performed by a surgeon specializing in these procedures. Patients of surgeons who do not perform as many procedures can have increased risks of complications, particularly of complications arising from incorrect placement and positioning of the acetabular component.
The incorrect placement and positioning may arise even when the surgeon understood and intended the acetabular component to be inserted and positioned correctly. This is true because in some techniques, the tools for actually installing the acetabular component are crude and provide an imprecise, unpredictable coarse positioning outcome.
It is known in some techniques to employ automated and/or computer-assisted navigation tools, for example, x-ray fluoroscopy or computer guidance systems. There are computer assisted surgery techniques that can help the surgeon in determining the correct orientation and placement of the acetabular component. However, current technology provides that at some point the surgeon is required to employ a hammer/mallet to physically strike a pin or alignment rod. The amount of force applied and the location of the application of the force are variables that have not been controlled by these navigation tools. Thus even when the acetabular component is properly positioned and oriented, when actually impacting the acetabular component into place the actual location and orientation can differ from the intended optimum location and orientation. In some cases the tools used can be used to determine that there is, in fact, some difference in the location and/or orientation. However, once again the surgeon must employ an impacting tool (e.g., the hammer/mallet) to strike the pin or alignment rod to attempt an adjustment. However the resulting location and orientation of the acetabular component after the adjustment may not be, in fact, the desired location and/or orientation. The more familiar that the surgeon is with the use and application of these adjustment tools can reduce the risk to a patient from a less preferred location or orientation. In some circumstances, quite large impacting forces are applied to the prosthesis by the mallet striking the rod; these forces make fine tuning difficult at best and there is risk of fracturing and/or shattering the acetabulum during these impacting steps.
Earlier patents issued to the present applicant have described problems associated with prosthesis installation, for example acetabular cup placement in total hip replacement surgery. See U.S. Pat. Nos. 9,168,154 and 9,220,612, which are hereby expressly incorporated by reference thereto in their entireties for all purposes. Even though hip replacement surgery has been one of the most successful operations, it continues to be plagued with a problem of inconsistent acetabular cup placement. Cup mal-positioning is the single greatest cause of hip instability, a major factor in polyethylene wear, osteolysis, impingement, component loosening and the need for hip revision surgery.
These incorporated patents explain that the process of cup implantation with a mallet is highly unreliable and a significant cause of this inconsistency. The patents note two specific problems associated with the use of the mallet. First is the fact that the surgeon is unable to consistently hit on the center point of the impaction plate, which causes undesirable torques and moment arms, leading to mal-alignment of the cup. Second, is the fact that the amount of force utilized in this process is non-standardized.
Traditionally these methods do not have any clear understanding of the forces, including magnitude and direction, involved in installing a prosthesis. A surgeon often relies on qualitative factors from tactile and auditory senses. Consequently, the surgeon is left somewhat haphazardly and variably relying on two different fixation methods (e.g., pins and press-fit) without knowing how or why.
In these patents there is presented a new apparatus and method of cup insertion which uses an oscillatory motion to insert the prosthesis. Prototypes have been developed and continue to be refined, and illustrate that vibratory force may allow insertion of the prosthesis with less force, as well, in some embodiments, of allowing simultaneous positioning and alignment of the implant.
There are other ways of breaking down of the large undesirable, torque-producing forces associated with the discrete blows of the mallet into a series of smaller, axially aligned controlled taps, which may achieve the same result incrementally, and in a stepwise fashion to those set forth in the incorporated patents, (with regard to, for example, cup insertion without unintended divergence).
There are two problems that may be considered independently, though some solutions may address both in a single solution. These problems include i) undesirable and unpredictable torques and moment arms that are related to the primitive method currently used by surgeons, which involves manually banging the mallet on an impaction plate mated to the prosthesis and ii) non-standardized and essentially uncontrolled and unquantized amounts of force utilized in these processes.
Total hip replacement has been one of the most successful orthopedic operations. However, as has been previously described in the incorporated applications, it continues to be plagued with the problem of inconsistent acetabular cup placement. Cup mal-positioning is a significant cause of hip instability, a major factor in polyethylene wear, osteolysis, impingement, component loosening, and the need for hip revision surgery.
Solutions in the incorporated applications generally relate to particular solutions that may not, in every situation and implementation, achieve desired goal(s) of a surgeon.
There are various sensing systems that may be used over a course of preparation and installation of a prosthesis, for example an acetabular cup. These sensing systems may detect various parameters such as an orientation angle of the prosthesis at any given time. These sensing systems may provide a set of periodic snapshots in time over the course of the procedure, but they do not provide true realtime continuous data over the installation procedure. That is, a surgeon may employ a sensing system to measure an orientation before striking an acetabular cup using a mallet and tamp, and may employ a sensing system to measure an orientation after striking the acetabular cup. But these sensing systems do not provide an orientation measurement (and in most cases no measurement of any information) during the strike. That is, the surgeon often measures, strikes, remeasures, restrikes, and repeats until the surgeon decides to stop. For a conventional system in which the surgeon manually swings the mallet and the installation model includes a sequence of discrete impulses from the mallet, this paradigm is understandable.
Some conventional systems may describe some measurements as “real time” but those systems are real time in the sense that the measurements are taken in the operating room during a procedure. The actual system does not provide realtime measurement during the actual insertion event.
In the incorporated applications, alternatives to the manual swinging of the mallet are described and in these systems the conventional measurement paradigm may be unnecessarily restrictive.
What is needed is a system and method for allowing any surgeon, including those surgeons who perform a fewer number of a replacement procedure as compared to a more experienced surgeon who performs a greater number of procedures, to provide an improved likelihood of a favorable outcome approaching, if not exceeding, a likelihood of a favorable outcome as performed by a very experienced surgeon with the replacement procedure, such as by understanding the prosthesis installation environment (e.g., cup/cavity interface) and to provide intelligent and interactive tools and methods to standardize the installation process.